Impeller agitator



Nov. 4, 1930.

A. W. BULL IMPELLER AGITATOR Filed March 25, 1929 INVENTOR A ri* h u r W. B

TTO EY Patented Nov. 4, 1930 NUNITED `"s'riras PATENT ori-ien ARTHUR W. BULL, or NAUCAUCK, CONNECTICUT, AssIGNn To THEl Lona Comm,

, or NEW Yoan, N. Y., A'CoRroBA'rIoN or DELAWARE IMPELLER miraron `Applcatin led March 25, 1929. Serial No. 349,732.

` This invention relates to agitators ofthe circulation type, in which a rotating impeller in the'tank produceswa vertical current with a return flow in the opposite direction. The

invention particularly relates to agitators of this type employing a draft tube surrounding the impeller for directingthe fluid circulation. l

When employed in continuous operation,

that is, with a continuous feed and discharge,

`agitators of this type are designed with relation to the flow so that the liquid tobe agitated will have a predetermined detention period adequate to produce the necessary mixing, dissolution, reaction or other. operation. However, it has been found that individual portions of the feed may not be retained in such agitators for the predeter- I mined detention period, as some portions of the feed may tend to short-circuit across the `agitator to discharge, while other portions are detained any abnormal length of time in the agitator. This condition is decidedly objectionable, particularly where complete chemical reaction between constituents is nec- 4.essary. .L e

The primary object of this invention is, therefore, to provide a circulation agitator, in-which direct short-circuit from the feed inlet to the discharge outlet will be positively prevented and detention for less than the desiredperiod will be minimized, this arrangement in turn resulting naturally in a correspondin elimination of excessive detention. This o ject is, in general, attained by connectin the draft tube with the tank walls as by ba es or partitions arranged so as to Y l4:5 of the draft tube is a substantial pro lem.

yThis object, likewise, is s olved by the use of the partitions above mentioned, which serve as convenient and strong supporting means for the draft tube. Where an upward central current is employed, a transverse 'partition-beneath the draft tube` may be installed, l

which positively preventspa'rticles descending on the vfeed side from shooting across the bottom and rising on the` outlet side of the draft 'tube which would tend to reduce their detention period; but this arrangement is distinctly alternative and optional, since ordinarily such particles would in any event be sucked up in the rising current. Likewise, a transverse partition above the draft tube may be employed, with the same result as where the partition is installed beneath the tube, the partition beneath the tube being retained, if desirable, so that there would be a partition entirely surrounding the tube.

.1t is to be understood that the apparatusV is not necessarily limited to an upward flow in the draft tube, since it will likewise operate with a downward flow on substantially the same principle. Furthermore, it. is not limited to the use of a mechanical impeller or propeller, as shown, since other lifting arrangements, such as compressed air or other gas, are known and in general use.

Other objects and advantages of the invention will be apparent fromdthe following description taken in connection with the accompanying drawings, in which Fig. 1 is a vertical sectional view of an embodiment of my invention;

Fig. 2 is a plan; and` Fig. 3 is an enlarged detail view, partly in section, showing the manner of attachment of the impeller to the shaft,`a nd also the foot bearing and its connection with the shaft and the supporting beam.

Referring to the drawings, 1 designates a tank made of reinforced, concrete or other suitable material and having at opposite sides thereof a feed inlet or launder 11 and a discharge outlet or launder 12 at substantially the normal liquid level in the tank. The tank is here .shown as square, but it should be understoodthatthe tank may be circular or of any other suitable conformation. Positioned centrally in the tank and between the feed inlet and the discharge outlet is a draft tube 13 with its upper end below the normal liquid level and its lower end'spaced above the bottom of the tank. Y

i is mounted on a vertical shaft 15 suspended cured thereto.

from a platfdrm 16 carried by cross members 17 in the form of I-beams and supported on opposite sides of the tank. The shaft is driven through a speed reducer18 by a motor 19, both of which are mounted on the platform 16; and at its lower end is guided or -maintained in alignment by a foot bearing 20 including a bushing 21 serving to receive the shaft and being adjustable for centering the shaftv by means lof threaded boltsor screws 22 mounted horizontally in a ange projecting upwardly from a plate 23 secured by bolts 24 to a crossbar or beam 2 5 extending across the draft tube intermediate its ends and se- The hub of the impeller is mounted on the shaft loosely enough to permit sliding and rests on a projection 26 on the shaft, said projection being preferably in the form of a pin; andrelative rotation between the shaft and the impeller is-prevented by suitable means such as a key or feather 27 entering suitable grooves in the shaft and impeller, the key 27 being tapered or of wedge shape so as to hold such members tightly together.

The structure thus far describedl may be substantially o f usual form. In operation the feed enters continuously at the inlet ll'and an equivalent amount oftreated fluid or liquid is displaced and overiiows Athrough the discharge outlet 12, but in passing through the tank .the liquid is subjected to the action of the impeller 14 which, as here shown, tends to produce iow of the liquid upwardly through the draft tube and downwardly at the periphery of the tank, as indicated by the arrows 1n 1g. 1. As already stated, individual portions o the feed material. may not be'retained in the agitator for the predetermined Adetention period,` due to a tendency to short circuiting across the tank to the discharge outlet, and

this action would be accompanied by detention for anabnormal or excessive length of time of other portions of the feed. Itwil1 be apparent that the flow at the outlet end of the draft tube tends to spread in all directions and therefore to prevent short circuiting at such end; and that short circuiting is more likely to occur at the sides of the draft tube and across the inlet end of the tube, althou h probably less likel at thev inlet end of t e tube than at the siv es.

According'to the illustrated embodiment of the invention, the agitator is provided with vertical partitions 3() extendln from the shaft tube 13 to the side walls o the tank 1, and substantially in a vertical plane passing through the axis of the draft tube and perpendicular to the vertical plane through the axis of the inlet and the outlet. This arrangement serves to prevent any portion of lthe tank for the the feed from passing around the draft tube at the sides thereof. These partitions may also extend to the bottom of the tank and upwardly above the normal liquid level.-

There may also be a transverse partition 31 extending across the lower or inlet end of c the draft tube'and serving positively to prethroughthe draft tube is downward. In l either case, it would be desirable to have the partition extend from the level ofthe innermost point of the inlet end of the tube tothe corresponding surface of the fluid at the top or 1pottom of the column of material in the tan Y Another important feature of the invention resides in the utilization of the partitions 30, the partition 31, or both of them to support the draft tube which may be .of reinforcedl concrete, and is of considerable Weight. To this end, the partitions 30 are connected directly with the draft tube and are supported by the side walls, floor or both;

and the draft tube rests on the partition 31. a

In order to support the draft/ tube 13 at points outside the plane of the partitions 30 and 31, there may be provided posts 32 interposed between the lower edge of the draft tube and the iioor of the tank.' Preferably there are two of such posts whichare arranged in the vertical plane between the inlet and the outlet.

It will'be apparent from the foregoing description that various modifications and changes in the arrangement shown may be made without departing from the s irit and scope of the invention.. In particular it should be understood that by partition is meant any structure connecting or inter osed between the draft tube and the side wa s of purposes indicated.-

I claim:

1. In an agitator, the combination with a.l tank having an inlet and an outlet spaced from each other, a relatively large open ended draft tube communicating at its lower end with the lower*- part of said tank and extending upwardly therefrom, and means for producing a current through said draft tube of means extending across the inlet en/dyo the tube in the tank and extending to the bottom of the tank and completely across the same for preventing the passage of liquidx tank having an'inlet and an outlet spaced' from each other, of a relatively large open ended draft tube, means extending from the draft tube to the wall of the tank attwo different positions and extending substantially throughout the'height of the tank to prevent passage of material in either direc'- tion around'the tube from said inlet to said outlet, said means having supporting engagement with the draft tube and means for producing a current through said draft tube.

3. In an agitator, the combination with a .tank having an inlet and an outlet spaced from 'each other, a draft tube in said tank communicating at its lower end with the lower part of said tank and extending upwardly, and means for producing a current through said draft tube, of a partition at c each side of the tank between the inlet and the outlet and extending from the draft tube to the tank and serving to support the 'draft `tube from the tank.

4; In an agitator, the combination with a tank having an inlet and outlet spaced from Eeach other, a relatively large open ended l tank and extending upwardly therefrom,

ing upwardly therefrom and having its upand means for producing a current through said draft tube, of a partition on each side of the tank between the inlet and the outlet 'and extending from the draft tube to the side wall of the tank and serving to support the draft tube in the tank.

5. In an agitator, the combination with a tank having an inlet and outlet spaced from each other, a relatively large open ended draft tube in said tank communicating at its lower end with the lower part of said tank and extending upwardly therefrom, and means for producing a current through said draft tube, of a partition at each side of the tank between the inlet and the outlet, extendtube said means having a. supporting engagementy with the draft tube. D

. 7. In an agitator, the combination with a l tank having an inlet and outlet spaced from each other, a relatively large open ended draft tube open at both ends communicating at its lower end with the lower part of said tank and having its upper open end below the solution level in the tank, and means for producing a current through said draft tube, of means extending across the inlet end of the tube in the tank between the inlet and the outlet for preventing passage of lquid from the inlet tov the outlet across' the inlet end of the tube, and means exten from 4the draft tube to the wall of the tank throughout the entire height of the same for preventing passage of liquid from the inlet to the houtlet around the draft tube, said means avi su portin enga ement with the draft tuin tlie tank.g g

8. In an agitator, the combination with a tank having an inlet and outlet spaced from each other, a relative] large open ended draft tube communicatlng at its lowerv end with the lower part of said tank and extending upwardly therefrom and means for producing a current through the tube, of partitions on .each vside of the draft tube between said inlet and said outlet, said partitions resting on the bottom of the tank and serving to support the draft tube in the tank, and additional means extending between the bottom of the tank and the'draft tube for supporting the same.

Intestimony whereof I aix In si ature.

ARTHUR ing from the draft tube to the bottom of the l tank and serving to support the draft tube in the tank.

6. In an` agitator, the combination with a tank having an inlet and outlet spaced from each other, a relatively large open ended draft tube. communicating at its lower end with the lower part of said tank and extendper end below the solution level in the tank and means for producing a current through said draft tube of a partition at each side of the tank between the inlet and the outlet and extending from the draft tube to the wall of the tank upwardly above the solution level in the tank for preventing the p of liquidv from the inlet to the outlet around said dmgso 

